In today's common rail fuel injectors, the quantity of fuel injected and the opening and closing times of the injector are dependent on the ability of the industrial means of production to produce the injectors while respecting the key parameters of the injector. Variations occur as a result thereof. In addition, during operating cycles of the fuel injectors, certain parameters arise because of wear in the components. The rise and fall times of the control valve, as well as those of the needle of the injection nozzle, can be mentioned here as examples. Strategies are available for the supervision of the movements of the needle, in particular by measuring the variation in a current injected through the injector, the position of the needle causing said current to vary. This type of solution requires the provision in the injector of resistive coatings and of electrical connections allowing a known electrical path to be achieved by the injected current. The putting in place in the injector of electrical connections allowing the diagnosis of the position of the needle by the injection of a current is an industrial challenge. Problems of the reliability of the connections during the life cycle of the injector, as well as problems of productivity associated with the assembly time for such an injector, have impeded the putting in place of control strategies of this type in fuel injectors. It is therefore important to propose a novel solution resolving these problems.